PLK1 regulation of PCNT cleavage ensures fidelity of centriole separation during mitotic exit.

Jaeyoun Kim,Kwanwoo Lee,Kunsoo Rhee

doi:10.1038/ncomms10076

Abstract

Centrioles are duplicated and segregated in close link to the cell cycle. During mitosis, daughter centrioles are disengaged and eventually separated from mother centrioles. New daughter centrioles may be generated only after centriole separation. Therefore, centriole separation is considered a licensing step for centriole duplication. It was previously known that separase specifically cleaves pericentrin (PCNT) during mitotic exit. Here we report that PCNT has to be phosphorylated by PLK1 to be a suitable substrate of separase. Phospho-resistant mutants of PCNT are not cleaved by separase and eventually inhibit centriole separation. Furthermore, phospho-mimetic PCNT mutants rescue centriole separation even in the presence of a PLK1 inhibitor. On the basis on these results, we propose that PLK1 phosphorylation is a priming step for separase-mediated cleavage of PCNT and eventually for centriole separation. PLK1 phosphorylation of PCNT provides an additional layer of regulatory mechanism to ensure the fidelity of centriole separation during mitotic exit.

Highlights

IntroductionDaughter centrioles are disengaged and eventually separated from mother centrioles
Centrioles are duplicated and segregated in close link to the cell cycle
The centrosomal levels of PCNT and CEP215 remained relatively abundant in the BI2536-treated cells even after mitotic exit (Fig. 1b–d)

Summary

Introduction

Daughter centrioles are disengaged and eventually separated from mother centrioles. On the basis on these results, we propose that PLK1 phosphorylation is a priming step for separase-mediated cleavage of PCNT and eventually for centriole separation. Once the cells undergo mitosis, daughter centrioles are disengaged and eventually separated from the mother centrioles. PCNT is phosphorylated by PLK1 and recruits other PCM proteins to assemble spindle. (b) Immunoblot analysis was carried out to determine the PCNT cleavage in PLK1-depleted HeLa cells during the forced mitotic exit. (e) Immunoblot analyses were carried out to determine specific cleavage of ectopic FLAG-PCNT7A-Myc (7A) and FLAG-PCNT9A-Myc (9A) during the forced mitotic exit. (f,g) Specific cleavage of ectopic FLAG-PCNT-Myc (WT) and FLAG-PCNT9D-Myc (9D) was determined in the presence of BI2536 (f) and in the separasedepleted cells (g).

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Results

Conclusion